The present disclosure relates to an illumination device, an image reading apparatus, and image forming apparatus using a light guide body for guiding illumination light emitted from a light source.
In an image forming apparatus such as a scanner or a copy machine, an illumination device that radiates light to a document sheet placed on a reading surface is used for optically reading an image of the document sheet. In recent years, an LED (Light Emitting Diode) which has an advantage of high light emission efficiency may be employed as a light source of the illumination device. This type of illumination device needs to radiate light in a line shape to a document sheet. Since an LED is a point light source, a bar-like light guide body and the LED are combined, to generate illumination light in a line shape. The light guide body has an incident surface which is located at one end of the light guide body and into which illumination light emitted from the LED enters, and an exit surface which extends along a longitudinal direction of the light guide body and from which the illumination light is emitted.
As a relevant technique, a technique is known in which one light guide body and a reflection plate extending in parallel to the light guide body are provided for illuminating a document sheet. The light guide body has two exit surfaces, and light emitted from one of the exit surfaces is directly radiated to a document sheet. In addition, light emitted from the other exit surface is reflected by the reflection plate, and then radiated to the document sheet. As a result, lights are radiated to the document sheet from two directions crossing each other.